The trend of humanity to progressively spend more time in space has spurred governmental and private interest in the concept of in-space manufacturing. The cost of exiting and entering Earth's atmosphere provides a clear economic incentive to manufacture parts in-orbit and/or outside of Earth's environment. For example, to repair space stations, satellites, space capsules, etc. Current capabilities, however, are highly limited. Onboard the International Space Station, for example, the National Aeronautics and Space Administration (NASA) operates two fused deposition modeling (FDM) three dimensional (3D) printers capable of printing plastic parts in the International Space Station's microgravity environment. FDM 3D printing, as well as most additive manufacturing processes, suffers from drawbacks. For example, some 3D printing techniques require a liquid or a powder substrate, which are poorly suited for microgravity. Other FDM 3D printing techniques are limited to low strength plastics. Finally, most additive manufacturing processes require an additional subtractive machining (finishing) process to achieve tolerances that are suitable for higher-precision spaceflight-certified hardware.
NASA has been actively developing a metal 3D printing technology called Electron-Beam Freeform Fabrication (EBF3), which builds slightly oversized (i.e., near-net) metal parts by continuously fusing a metal feed spool using an electron beam. By design, the technology is ideal for microgravity and is highly efficient in terms of energy and material usage, but has limitations associated with the relatively large and difficult-to-control diameter of the molten metal pool that forms as the component part is built. Consequently, EBF3-made components have surface finishes and tolerances well below standard/expected values employed in engineering work. For example, components deposited by the EBF3 process typically exhibit a characteristically rough, layered surface finish. Further, wall thicknesses and surface finishes are both highly dependent on the properties of the molten metal pool. To refine EBF3 deposited components, a subtractive post machining process may be employed to remove amounts of material to bring the near-net part to the desired net shape (i.e., final size/shape). However, there is currently no means of performing subtractive machining in microgravity. Therefore, a need exists for a system, method, and apparatus for performing subtractive machining in microgravity.